Welding electrode with lithium shielding metal

ABSTRACT

An electric arc welding electrode comprised principally of an elongated steel member having associated therewith lithium alloyed with or coated over with other low boiling temperature metals plus metals of higher melting temperatures for delaying the boiling action of the low boiling temperature metals. The member may be striated and these metals fill the striations.

United States Patent Landis et al. [451 Sept. 12, 1972 [54] WELDINGELECTRODE WITH 3,081,534 3/1963 Bredzs., ..75/148 X LITHIUM SHIELDINGMETAL 3,272,624 951966 Quaas ..75/138 1,620,082 3 1927 Czochialski 75/138 [721 lnvemrs= hndis, Cleveland; John 2,087,269 7/1937 Stroup..75/138 Parks, Solon; Kenneth Brown, 2,505,937 5/1950 Bernard..29/191.6 x South Euclld, all of Ohm 2,062,457 12/1936 Johnston 148/24x 73 A Th Li In E] m C 2,282,175 5/1942 Emerson ..148/24 1 s f Ohio2,052,740 9/1936 Barer et a1, ..29/191.6 x 3,468,695 9/ 1969 Federman..29/ 191.6 X [22] Filed: Jan. 13, 1970 867,659 10/1907 Hoopes et a1..29/ 191.6 2,915,391 12/1959 Criner ..75/138 X [21] 2643 3,073,7201/1963 M618 ..75/138 x m A li fi 309,439 12/1884 Chillingworth et a]...29/19 1 .6

[63] Continuation-impart of Ser. No. 618,979, Feb. PrimaryExaminer-Allen B. Curtis 27, 1967, abandoned, Continuation-impart 0fAttorney-Meyer, Tilberry and Body Ser. No. 493,615, Sept. 24, 1965,abandoned, Continuation-impart of Ser. No. 289,871, June ABSTRACT 1963abandoned An electric arc welding electrode comprised principally of anelongated steel member having asg [52] U.S. Cl. ..219/146, 29/ 191.6,75/138, sedated therewith lithium alloyed with or coated over 148/24219/137 with other low boiling temperature metals plus metals [5 Int.Cl. of melting temperatures for delaying the Field 01 Search action ofthe low boiling temperature metals. The 75/138, 289, 871, 493, 615, 618,979 member may be striated and these metals fill the striations. [56]Rem-wees Cited 12 Claims, 7 Drawing Figures UNITED STATES PATENTSPATENTEUSEP 12 I972 INVENTOR GEORGE G. LANDIS JOHN M. PARKS KENNETHL.BROWN T MOQ; W AT ORNEYS.

WELDING ELECTRODE WITH LITHIUM SHIELDING METAL This application is acontinuation-in-part of our copending application, Ser. No. 618,979filed Feb. 27, 1967, now abandoned, which is a continuation-in-part ofour copending application, Ser. No. 493,615, filed Sept. 24, 1965, nowabandoned, which is a continuation-in-part of our application Ser. No.289,871, filed June 24, 1963, now abandoned.

This invention pertains to the art of electric arc welding and moreparticularly to welding with a bare metal electrode without the use ofnon-metallic fluxes or shielding gases.

In the past numerous methods and arrangements have been employed toshield the electric are from the atmosphere, all of which have hadvarious difficulties which the present invention attempts to overcome.

For example, various non-metallic fluxing materials have been coated ona metal core wire. These materials either melt and/or vaporize in theheat of the arc to exclude the atmosphere and protect the deposited weldmetal until it solidifies. Coated electrodes, while used extensively,have certain difficulties. They are relatively expensive to manufacture.They leave a slag on top of the weld bead which must be removed.Sometimes this slag clings tenaciously to the weld bead and is difficultto remove. Furthermore, continuous or auto-- matic welding has beenpractically impossible with coated electrodes. The coating is anelectrical insulator and it is economically unfeasible to energize thecore wire through the coating. Thus the electrodes are made relativelyshort and the end opposite the arcing end is bared of coating andelectrical contact is made on this end. The length of such an electrodeis limited because of the heating effects of the electric currentflowing through long lengths of the core wire for' prolonged periods.

A granulated flux material has also been employed which is deposited asa windrow on the weld seam. A bare electrically energized electrode isadvanced through this flux toward the workpiece and an arc is maintainedunderneath the flux. The flux serves the function of shielding thebrilliant glare of the arc from the eyes of the operator as well asmelting and vaporizing to protect the arc from the surroundingatmosphere. Using granulated flux, it is possible to use a bareelectrode whichis continually advanced toward the workpiece and only asmall length of the electrode is carrying electric current at any timebut the weld pool is at all times obscured from the operator.

The use of granulated flux is messy, expensive and requires the feedingof two distinct materials simultaneously to the arc; namely, the fluxand the electrode.

The inert gases have also been employed to shield the are from theeffects of the atmosphere. These gases are flowed from storage tanksthrough flexible hoses to the tip of a welding gun, which in some cases,contains intricate wire feed mechanism. Particularly where a wire feedmechanism is built into the welding gun, it is conventional to employwater cooling to conduct away the radiated heat of the are which wouldotherwise damage such mechanism. In any event, the storage tanks arethemselves bulky and heavy. Additionally, the flexible hoses to feed theinert gas and the cooling water passes in the welding gun add to thebulk an intricacy of an already bulky and complicated device. Further,the inert gases are relatively expensive.

bon dioxide gas mixtures. Such method, while extremely effective, stillrequires the use of a separate source of shielding gas with its bulkyand heavy tank, an unwieldy hose and cumbersome welding heads.

US. Pat. No. 2,909,648, dated Oct. 20, 1959 and assigned to the assigneeof this application, proposes a solution to these problems and describesthe use of a metallic coating on the surface of a steel electrode, whichcoating vaporizes in the heat of the arc to provide a metallic vaporshield around the arc and exclude the atmosphere from the vicinity ofthe molten weld pool. At the time that the application resulting in thatpatent was filed, it was believed that the upper limit on the boilingtemperature of the metal of this coating should be the boilingtemperature of the metal being welded, which in the case of steel isapproximately 2,800C. Further research on the use of metals to produce ametallic vapor shield now indicates that the maximum boiling temperatureof the shielding metal should not exceed the melting temperature of theelectrode, which for steel is 1,535C. Also, such research indicates thatthere is one metal not included in that patent having a boilingtemperature below the melting temperature of steel (1,535C), which isnot only desirable but necessary to obtain sound weld beads.

Of these various metals, some result in lower voltage gradients in thearc than others. Lithium is the lowest and tends to produce a broaddiffuse arc which heats the plate being welded more uniformly than asharply defined arc. Also the arc temperature, when lithium is present,is below 5,500K, the disassociation temperature of nitrogen. Nitrogen inthe disassociated state is quite reactive and is picked up readily bythe weld pool.

In accordance with the invention, at least lithium is always employed asa shielding metal. The minimum amount of lithium required in accordancewith the invention is that required to shield the arc while the maximum.is dictated by the economics of welding. Lithium is expensive. From0.05 to 1 percent of the total electrode weight is lithium in accordancewith the inventron.

Other metals may be used to supplement the shielding action of lithium.These supplementary shielding metals should have the followingcharacteristics:

1. a melting temperature less than the melting temperature of steel(1,535C);

2. a chemical inertness to nitrogen at temperatures ranging fromslightly below to above the melting temperature of steel;

3. a boiling temperature not in excess of the melting temperature of thesteel;

4. an alloying characteristic with steel which is not detrimental to thestrength, ductility, etc. I

Many metals having boiling temperatures less than the meltingtemperature of steel (1,535C) fall into these four classifications. Manyof these metals, however, because of their expense, unavailability ortoxicity either of the metal itself or of its oxide, would only beemployed in a laboratory and may thus be excluded from the practicalaspects of the invention.

Of these metals having a moderate cost, the following fall within thefour classifications: noted above barium, cadmium, zinc, magnesium,strontium, sodium, potassium, calcium and bismuth. Accordingly, thesecome within the scope of the invention and one or more of such metalsmay be used in conjunction with lithium. While the shielding metals maybe used in any amount, a preferred quantity of shielding metal willcomprise from 0.05 to about 5.0 percent by weight of .the electrode.

It is to be noted that U.S. Pat. No. 2,909,648 lists some of thesemetals as a shielding metal, namely, bismuth, cadmium and strontium, andinsofar as these three metals are employed without lithium, they areexcluded from the present invention. However, such metals if used incombination with other features of the invention are then included.

These metals, referred to generically hereinafter as shielding metals,may be fed into the arc in any desired manner such that they willvaporize and create a cloud of metallic vapor shielding the are from theelectrode tip to and including the molten weld pool; for example, on theinside of a tube, as a separately fed strip or ribbon, but preferablyand in accordance with one phase of the invention, as a thin uniformcoating around the surface ofa solid steel core or tube.

When these metals are fed into the are as a coating on the externalsurface of a steel core or tube, it is necessary, in accordance with theinvention, that the coating or coatings, if there be more than one, beso bonded to the steel core or the immediate underlaying coating as tohave the maximum degree of heat conductivity therebetween. Normally, toobtain such heat conductivity, the various coatings must bemetallurgically bonded.

Depending on the mode of applying the shielding metal, not all of thoseabove listed will metallurgically bond to a steel core and if with theparticular shielding metals selected such metallurgical bonding cannotbe obtained, then in accordance with the invention, the shielding metalis either alloyed with a metal which will itself bond with the steelcore or an intermediate layer of a metal is first applied to the steelcore, which metal will metallurgically bond both with the steel core andwith the shielding metal or the metal with which the shielding metal isalloyed. Metals which readily metallurgically bond to steel and whichare low in cost and easily applied are zinc, copper, aluminum, tin andcadmium. Normally, these metals will be applied in what may be termed aflash or strike of a thickness of 0.001 inch. It is to be noted thatsome of these metals, for example, zinc and cadmium, can thus serve bothas a bonding metal and as a shielding metal. If the bonding metal is tobe made of zinc or cadmium, it can be have a slightly greater thicknessthan just stated. It is to be noted that the oxides of zinc and cadmiumare considered somewhat toxic so that these metals should not be used toexcess.

For the maximum protection of the are from the atmosphere, it isnecessary that the production of the metallic vapor start at least ashort distance above the arcing tip of the electrode and preferablycontinue on down to the actual arcing tip of the electrode. With theshielding metals listed, it will be appreciated that with boilingtemperatures below the melting temperature of steel, they will haveboiled off from the surfaces of the steel core before reaching theactual arcing tip of the electrode. Thus, the invention contemplatesmeans for modifying the boiling action of the shielding meal'so that itcommences to boil at a point on the electrode slightly spaced from thearcing tip and continues to boil down to the arcing tip of theelectrode. Such modifying means may, in accordance with the invention,be a metal having a melting or boiling temperature above the boilingtemperature of the shielding metal(s) itself or both. Thus, if lithiumhaving a low boiling temperature (1,370C) is alloyed with a modifyingmetal such as aluminum having a boiling temperature of 2,330C

and such alloy is coated onto a steel core, the lithium commences toboil when it reaches its boiling temperature but due to the proximity ofthe lithium to the aluminum with a much higher boiling temperature, thecompletion of the boiling action of the lithium is retarded until thealuminum itself reaches the boiling temperature close to or at thearcing tip of the electrode such that the shielding metal is able toperform its shielding action over the maximum distance. It is also to benoted that by so modifying or retarding the boiling action of thelithium, then any beneficial effects of the shielding metal on theaction of the arc itself such as confining the arc in a manner similarto shielding gases such as helium, can be enhanced.

The modifier for retarding the boiling action of the shielding metal(s)must have generally the following further characteristics:

1. A boiling temperature substantially in excess of the meltingtemperature of steel and preferably close to or slightly above thetemperature of the molten metal in the weld pool which measurements haveindicated to be on the order of 2,1 00 to 2,200C; and,

2. An alloying characteristic with steel which is not detrimental to itsstrength, ductility and the like.

Modifying metals fitting within this general classification aregenerally: manganese, lead, aluminum, silicon, cobalt, copper andnickel. While any quantity of modifier metal may be employed, apreferred quantity is between about 0.05 and about 10.0 percent of theelectrode weight.

It is to be noted that of these metals, aluminum, silicon and manganeseare considered to be desirable killing agents with manganese the least.On the other hand, manganese in even relatively large amounts isconsidered to be a desirable alloying agent while silicon in somewhatlesser amounts is considered to be a desirable alloying agent. Smallamounts of aluminum also contribute to grain refinement.

At room temperatures, many of the shielding metals listed, e.g., all ofthose except cadmium and zinc, are quite reactive with the oxygen in theatmosphere, particularly in the presence of the humidity of theatmosphere and this appears-to be so even though the shielding metal(s)is alloyed with a modifier metal such as aluminum prior to being coatedon the steel core such that an electrode which welds satisfactorilyimmediately after manufacture, will not after exposure to the atmospherefor relatively brief periods of time, from an hour to several days, weldsatisfactorily. Thus, the invention further contemplates some form ofprotector which will prevent the shielding metal(s) or its alloy fromreacting with the atmosphere and deteriorating. Such shielding metalprotector may be a thin coat or strike of a material which isnon-reactive to the atmosphere even in high humidity, for example, acoating of antimony, aluminum, magnesium, zinc, nickel, silver, tin,lead, copper, cadmium or manganese, either as elements or alloys or maybean organic coating such as mineral oil or the like which will excludethe atmosphere from the highly reactive shielding metals. Alternativelythe portion of the shielding metal at the outer surface of the coatingmay be reacted with an elementor compound which will in turn from acompound which is impervious to water vapor. Nickel is a preferredprotector metal and is preferably employed in amounts comprising betweenabout 1 and about percent of the total electrode weight.

The various coatings of metals above described may be applied to theelectrode core in any desired manner, such as dipping, that is to say,passing the electrode through a molten bath of the desired metal(s),electroplating, spraying or vacuum deposition. Spraying or dipping ispreferred. The particular method employed will depend on the nature ofthe metal or alloy employed. In any event, it is necessary or desirableto thoroughly clean the surface of the steel core preparatory towhatever coating process is employed and it is also desirable ornecessary to protect the electrode from the atmosphere as it passes fromone coating process to the next.

The electrode core, as previously stated, may be either a solid steelwire, or a tube which may or may not have on the inside ingredientswhich will further contribute to the shielding of the are or thealloying of the deposit of weld bead and the wire may have one or morestriations formed along its surface which are filled by the shieldingand modifier metals. In this respect it is to be noted that there is asubstantial difference when a particular metal is fed into the arc onthe outside of either a tube or a solid core. in the former instance,the efficiency of the transfer of the metals is much better than in thelatter case. i

In any welding of ordinary low carbon steel, it is usually necessary tohave some killing agent such as manganese, silicon or aluminum whichwill be carried over into the weld pool. These metals assist inpreventing porosity of the weld bead and otherwise contribute to theoverall strength and ductility thereof. If one or more of these meals isincluded in the coating, then the steel core may be of plain low carbonsteel having no or a minimum amount of alloying ingredients such assilicon or manganese. If none of these three meals are used in thecoating, then the steel of the core should preferably have one or moreof these three metals alloyed therewith. It is further to be noted thatsome silicon is desirably present either in the electrode core or in thecoating for the reason that the silicon, at least in part, reacts withplate scale (iron oxide) or with oxygen in the atmosphere to formsilicon dioxide. Silicon dioxide is an excellent wetting agent to steeland assists in the formation of a desirable bead shape.

The total composition of the electrode to be em- Thus for verticalwelding there must either be a spray transfer of metal from theelectrode to the workpiece or drop transfer. lf drop transfer isemployed, the arc characteristics must be such that the molten drops asthey are formed on the electrode end are transferred into the weld poolby the forces of the surface tension of the molten metals.

For any given electrode material and coating thereon, there is a currentbelow which the electrode end melts and forms droplets and above whichthe electrode metal is projected to the workpiece as fast as it becomesliquid such that the drops do not have time to form and the metal goesto the workpiece in what is known as a spray transfer.

For any given thickness of workpiece there is generally a maximumcurrent which can be employed so that it is not always possible to usewelding currents of the type which will give a spray transfer.

For vertical welds of relatively thin workpieces, e.g., one-eighth of aninch or less, currents on the order of to 350 amp. are normallyemployed. These currents are generally insufficient to give a spraytransfer and thus for such workpieces a drop transfer type of weldingmust be employed.

Lithium and other shield metals and modifiers may be mixed or alloyed inany desired ratios but from 1-25 percent lithium and the balancemodifier and the other shielding metals is in accordance with theinvention. The total of the two groups of metals to the electrode weightis in the range of 0. 10 to 10 percent.

A still further problem is applying the lithium and other metals if usedto the steel base wire in uniform amounts over long lengths of wire. Thepresent invention accomplishes this result by roughening the surface ofthe wire so that the shield metals will fill the depressions formed bysuch roughening. I

The principal object of the invention is the provision of a new andimproved base welding electrode which enables the welding in air withoutthe use of independently supplied shielding gases or welding fluxes.

Another object of the invention is the provision of a new and improvedwelding electrode which employs the use of metal vapors to. shield theare from the atmosphere.

Another object of the invention is the provision of a new and improvedwelding electrode which enables sound weld beads to be obtained usingrelatively simple welding apparatus.

Another object of the invention is the provision of a new and improvedwelding electrode having a coating of lithium on its outer surface,which lithium can vaporize in the heat of the arc to shield the are fromthe atmosphere.

Still another object of the invention is the provision of a new andimproved welding electrode which has many of the characteristics of agas shielded arc but which does not require the use of independentlysupplied gases.

Still another object of the invention is the provision of a new andimproved welding electrode having metals coated on the outer surfacethereof which assists in the transfer of the metal from the electrodetip to the weld pool.

Another object of the invention is the provision of a new and improvedarrangement for including lithium as a coating on a welding electrode.

Another object of the invention is the provision of a new and improvedwelding electrode which has a coating or coatings of metals thereonwhich metals have a range of boiling temperatures such as to protect theare from the atmosphere.

Still another object of the invention is the provision of a new andimproved welding electrode which has a coating containing at leastlithium and an exterior coating sufficient to protect the lithium orlithium alloy from reacting with the atmosphere.

The invention, of course, in its preferred embodiment, may take physicalform in a number of different arrangements, preferred embodiments ofwhich will be described in greater detail in this specification andillustrated in the accompanying drawing:

FIG. 1 is a cross-sectional view greatly enlarged of a welding electrodeillustrating a preferred embodiment of the invention;

FIG. 2 is a cross-sectional view similar to FIG. 1 illustrating analternative embodiment of the invention;

FIG. 3 is a cross-sectional view greatly enlarged illustrating a stillfurther alternative embodiment of the invention;

FIG. 4 is a cross-sectional view of the steel base wire of FIG. 3showing the position of the forming rolls for grooving or striating thecore wire;

FIG. 5 is a side elevational view somewhat schematic showing thelocation of the rolls for grooving or striating the core wire; and

FIGS. 6 and 7 are side elevational views partly in cross-section andsomewhat schematic showing the steps of coating the core wire.

Referring now to the drawings wherein the showings are for the purposesof illustrating preferred embodiments of the invention only and not forthe purposes of limiting same, FIG. 1 shows 5 short section of a weldingelectrode of indeterminate length which is adapted to be electricallyenergized and continuously fed towards a workpiece while an arc ismaintained between the end of the electrode and the workpiece tocontinuously melt off the end of the electrode and deposit the moltenmetal in a pool on the workpiece.

The electrode shown in comprised generally of a core 10, a first coating11 which normally includes a shielding metal and a modifier therefor anda second coating 12.

The core 10 in the preferred embodiment is low carbon steel having 0.5percent silicon and 1 percent manganese and a diameter of approximately0.045 inch. Obviously, the invention is not limited to the use of thisspecific metallurgical analysis of the core nor to this diameter. Inaccordance with the invention, the core may have a range of from onethirty-second to oneeighth inch.

The coating 11 in the preferred embodiment is comprised of an alloy asfollows in percents by weight:

In all instances it is to be noted that the aluminum, nickel and/orsilicon are modifiers for the basic shielding metal and these modifiermetals retard the boiling action of the shielding metal so that itcommences to boil at a point spaced from the arcing tip and continues toboil down to and including the arcing tip of the electrode.

It is obvious that the amount of lithium employed on a given electrodemay be varied either by varying the thickness of the coating 11 or byvarying the percentage of the lithium in the alloy of the coating 1 l orboth.

The coating 12 in the preferred embodiment is aluminum of a thickness ofapproximately 0.001 inch. Obviously, a greater thickness of aluminum maybe used. The major function of this coating 12 is to protect the lithiumin the coating 11 from the atmosphere. A minor function in the case ofaluminum is to retard the melting and boiling of the lithium.

FIG. 2 shows a section of a continuous indeterminate length of electrodecomprised of a core 20, a bond coating 21, a shielding metal coating 22and a protective coating 23.

The core may be of a metallurgical analysis similar to that of core 10or may be ordinary low carbon steel containing no alloying agents, itbeing noted that when aluminum or silicon are placed in the externalcoating 22, that it is ordinarily not necessary to include alloyingingredients or killing agents in the core 20.

The coating 21 is comprised generally of a strike of copper in athickness of 0.0001 inch. This coating can also be barium, aluminum,cadmium, nickel or zinc, it being noted that the prime requirement ofthis coating is to provide a metallurgical bonding agent between thesteel core 20 and the coating 22.

The coating 22 in the embodiment shown in FIG. 2 may have the samecompositions as those described with reference to the coating 11 of FIG.1.

In a like manner, the coating 23 may be aluminum or nickel having athickness of from 0.001 inch up to the thickness of the coating 22.

It is to be noted that in some instances the coating 12 or the coating23 can be of a mineral oil or the like, if the only function of thiscoating is to protect the shielding metals in the coatings 11 or 22 fromthe atmosphere. Such oils are not detrimental to the welding. They burnor are otherwise consumed in the atmosphere and ordinarily there is nocarbon recovery in the metal of the weld bead.

In the embodiment of the invention shown in FIG. 3 the core instead ofhaving circular cross-section as in the embodiment of FIG. 1 isgenerally in the configuration of a six-pointed star, being comprised ofa central body 52 and six integral points or lobes 53 projectingradially outwardly from the body 52 and being equally spaced around theperiphery thereof. These lobes 53 define a plurality of longitudinallyextending striations or grooves 54 and these grooves along with theouter surface of the lobes 53 are filled and covered, respectively, witha shielding meal of metal composition as described with reference toFIG. 1.

The surfaces of the lobes 53 and thus the surfaces of the grooves 52 areshown as having plane surfaces which intersect at a definite angle.Obviously these surfaces may be arcuate and intersect tangentially. Moreor fewer lobes can be provided so long as at least a portion of theintersecting surfaces provide a concavity or outwardly facing groove,with groove receives and retains the shielding metal.

The depth of the grooves may be as desired, depending upon the desiredpercentage weight of shielding metal in relation to the total weight ofthe electrode, or in relation to the weight of the steel core. In thepreferred embodiment, the outer surfaces of the lobes 51 define a circle0.045 inch in diameter and the maximum depth of each groove measuredfrom the circle is between 0.007 and 0.0014 inch.

FIGS. 3 and 4 show how the lobes 53 and grooves 54 are formed. Acylindrical wire 60 is advanced along a path of movement and at onepoint on this path of movement three grooved rolls 62 are mounted forrotation on axes which intersect at a 120 angle. These rolls each have atapered groove 64 in their outer surface having an included angle of 60.These rolls 62 may be mounted in any conventional manner, not shown, sothat they can exert very high radial forces on'the cylindrical wire. Thewire 65 with the shape of that shown in FIGS. 3 and 5 leaves the rollsand as shown in FIG. 6 is then passed through a molten bath 70 of thedesired shielding metal from where it emerges as a coated electrode 71with the shielding metal 72 filling the grooves and coating the outersurface of the lobes 53 as is shown in FIG. 5.

Because of the grooves, larger amounts of shielding metal in relation tothe total electrode weight can be readily obtained. Furthermore, the useof these grooves enables for greater accuracy of weight of shieldingmetal in relation to the total weight of the electrode than isobtainable with the circular configuration of FIG. 1. After the moltenmetal has congealed, various means can be employed for the purpose ofprotecting the lithium of the coating from the adverse effects of theatmosphere. Inasmuch as lithium is extremely reactive with water,non-aqueous means must be employed for this purpose. A protective metalcoating may be hot sprayed on or the coated electrode 71 may be passedthrough a material which will react with minor amounts of the lithium onthe surface of the coating to form a compound which is resistant orimpervious to water and water vapor and thus will prevent the remainderof the lithium below the surface of the coating from further reactionwith the moisture of the atmosphere.

In accordance with the preferred embodiment of the invention, theelectrode 71 after it leaves the coating bath 70 and before it is cooledfully is passed through a bath of a fatty acid such as steric acid 73heated to a temperature between 200 and 400C at which temperatures theacid will react with the lithium to form lithium stearate, a compoundwhich is resistant to water and water vapor. The stearic acid also coatsthe electrode surface with an oily film further protecting the lithium.

It will be appreciated that the electrode is what may be termed a bareelectrode in that there. is no nonmetallic coating on the outside of atype which will prevent electrical contact with the metal of theelectrode. Thus, by bare is meant an electrode which may be continuouslycontacted by sliding contact to electrically energize the electroderelative to the workpiece.

It is also appreciated that the electrode is capable of depositing weldbeads while welding in the air. By welding in air is meant that thereare no independently supplied welding fluxes or shielding gases. This isnot to say that auxiliary shielding gases or granular flexes cannot alsobe employed.

The invention has been described with reference to a preferredembodiment. Obviously modifications and alterations will occur to othersupon reading and understanding of this specification and it is myintention to include such alternations and modifications insofar as theycome within the scope of the appended claims.

Having thus described our invention, we claim:

1. A welding electrode comprised of a steel base wire having on theexterior surface thereof a coating comprised of lithium alloyed with oneor more modifier metals selected from the class consisting of aluminum,silicon, manganese, lead, nickel, cobalt and copper in approximateratios of 10-25 percent lithium and the balance comprising modifiermetals and an exterior coating of one or more metals selected from theclass consisting of aluminum, manganese, magnesium, lead,

copper, silver, tin, nickel, cadmium and zinc and all of said metalshaving a weight of from 0.10 to 10 percent of the total weight of theelectrode.

2. A welding electrode comprised of an elongated steel member incombination with an alloy comprised of lithium and aluminum inapproximate ratios of l0-25 percent lithium and the balance comprisingaluminum and having a weight of from 0.10 to 10 percent of the totalweight of the electrode.

3. The electrode of claim 2 wherein the combination includes nickel inapproximate amounts of form l-20 percent of the weight of the electrode.

4. The electrode of claim 1 wherein said coating includes an outer layerof nickel in approximate amounts of from l-20 percent of the totalweight of the electrode.

5. A welding electrode capable of welding in the air without the use ofexternally supplied fluxes or gases comprised of an elongated steelnumber in combination with an alloy of one or more metals capable ofvaporizing and shielding the are from the atmosphere selected from theclass consisting of: cadmium, zinc, magnesium, lithium, strontium,sodium, potassium, calcium and bismuth and one or more modifier metalscapable of delaying the boiling of such shielding metals selected fromthe class consisting of aluminum, silicon, manganese, nickel, cobalt,lead, silver and copper, the shielding metal being present inproportions of from 0.05 to 5.0 percent of the weight of the electrodeand the modifier metal being present in amounts of from 0.5 to 10percent of the total weight of the electrode, the shielding metals andmodifier metals being mixed in appropriate proportions of from 10-25percent lithium and the balance comprising non-lithium shielding metalsand modifier metals and the alloy of the shielding and modifier meals ispresent in amounts of from 0.10 to 10 percent of the total weight of theelectrode.

6. A welding electrode capable of welding in the air without the use ofexternally supplied fluxes or gases comprised of an elongated steelmember in combination with an alloy of one or more metals capable ofvaporizing and shielding the arc from the atmosphere selected from theclass consisting of: cadmium, zinc,

magnesium, lithium, strontium, sodium, potassium, calcium and bismuthand one or more modifier metals capable of delaying the boiling of suchshielding metals selected from the class consisting of aluminum,silicon,

manganese, nickel, cobalt, lead, silver and copper, the shielding metalessentially containing from -25 percent by weight lithium and beingpresent in proportions of from 0.05 to 5.0 percent of the weight of theelectrode and the modifier metal being present in amounts of from 0.05to 10 percent of the total weight of the electrode and a second andouter coating consisting of a metal selected from the class consistingof: aluminum, antimony, magnesium, zinc, nickel, silver, tin, lead,copper, cadmium, or manganese.

7. A welding electrode comprised: of a steel wire having a plurality oflongitudinally extending grooves, said grooves being filled with metalscapable of vaporizing in the heat of the arc and providing a shield ofmetallic vapor, said metals including lithium and one or moremetalsselected from the class consisting of barium, cadmium, zinc,magnesium, strontium, sodium, potassium, calcium, and bismuth and one ormore modifier metals selected from the class consisting of aluminum,manganese, lead, copper, silver and tin, said lithium comprising between10-25 percent of the total of said metals.

8. The electrode of claim 7 wherein said electrode has a coating of ametallic compound of a fatty acid.

9. The electrode of claim 7 wherein said wire has six longitudinallyextending lobes defining a like number of longitudinally extendinggrooves.

10. A welding electrode comprised of: a steel wire having a plurality oflongitudinally extending lobes defining a plurality of longitudinallyextending grooves in the surface of said wire; said grooves containing aplurality of shielding metals, one of which is lithium, plus one or moreshielding metals selected from the class consisting of barium, cadmium,zinc, magnesium, strontium, sodium, potassium, calcium and bismuth, saidlithium comprising 10-25 percent of said shielding metals.

11. The electrode of claim 10 wherein said metals are comprised oflithium and aluminum in approximate ratios of 10-25 percent lithium andthe balance comprising aluminum.

12. The electrode of claim 10 wherein said metals are comprised of atleast 10-25 percent lithium and the balance is comprised of one or'moremetals selected from the class consisting of aluminum, manganese, lead,magnesium, copper, silver, tin, nickel, cadmium and zinc, sodium,potassium and calcium.

1. A welding electrode comprised of a steel base wire having on theexterior surface thereof a coating comprised of lithium alloyed with oneor more modifier metals selected from the class consisting of aluminum,silicon, manganese, lead, nickel, cobalt and copper in approximateratios of 10-25 percent lithium and the balance comprising modifiermetals and an exterior coating of one or more metals selected from theclass consisting of aluminum, manganese, magnesium, lead, copper,silver, tin, nickel, cadmium and zinc and all of said metals having aweight of from 0.10 to 10 percent of the total weight of the electrode.2. A welding electrode comprised of an elongated steel member incombination with an alloy comprised of lithium and aluminum inapproximate ratios of 10-25 percent lithium and the balance comprisingaluminum and having a weight of from 0.10 to 10 percent of the totalweight of the electrode.
 3. The electrode of claim 2 wherein thecombination includes nickel in approximate amounts of form 1-20 percentof the weight of the electrode.
 4. The electrode of claim 1 wherein saidcoating includes an outer layer of nickel in approximate amounts of from1-20 percent of the total weight of the electrode.
 5. A weldingelectrode capable of welding in the air without the use of externallysupplied fluxes or gases comprised of an elongated steel number incombination with an alloy of one or more metals capable of vaporizingand shielding the arc from the atmosphere selected from the classconsisting of: cadmium, zinc, magnesium, lithium, strontium, sodium,potassium, calcium and bismuth and one or more modifier metals capableof delaying the boiling of such shielding metals selected from the classconsisting of aluminum, silicon, manganese, nickel, cobalt, lead, silverand copper, the shielding metal being present in proportions of from0.05 to 5.0 percent of the weight of the electrode and the modifiermetal being present in amounts of from 0.5 to 10 percent of the totalweight of the electrode, the shielding metals and modifier metals beingmixed in appropriate proportions of from 10- 25 percent lithium and thebalance comprising non-lithium shielding metals and modifier metals andthe alloy of the shielding and modifier meals is present in amounts offrom 0.10 to 10 percent of the total weight of the electrode.
 6. Awelding electrode capable of welding in the air without the use ofexternally supplied fluxes or gases comprised of an elongated steelmember in combination with an alloy of one or more metals capable ofvaporizing and shielding the arc from the atmosphere selected from theclass consisting of: cadmium, zinc, magnesium, lithium, strontium,sodium, potassium, calcium and bismuth and one or more modifier metalscapable of delaying the boiling of such shielding metals selected fromthe class consisting of aluminum, silicon, manganese, nickel, cobalt,lead, silver and copper, the shielding metal essentially containing from10-25 percent by weight lithium and being present in proportions of from0.05 to 5.0 percent of the weight of the electrode and the modifiermetal being Present in amounts of from 0.05 to 10 percent of the totalweight of the electrode and a second and outer coating consisting of ametal selected from the class consisting of: aluminum, antimony,magnesium, zinc, nickel, silver, tin, lead, copper, cadmium, ormanganese.
 7. A welding electrode comprised: of a steel wire having aplurality of longitudinally extending grooves, said grooves being filledwith metals capable of vaporizing in the heat of the arc and providing ashield of metallic vapor, said metals including lithium and one or moremetals selected from the class consisting of barium, cadmium, zinc,magnesium, strontium, sodium, potassium, calcium, and bismuth and one ormore modifier metals selected from the class consisting of aluminum,manganese, lead, copper, silver and tin, said lithium comprising between10-25 percent of the total of said metals.
 8. The electrode of claim 7wherein said electrode has a coating of a metallic compound of a fattyacid.
 9. The electrode of claim 7 wherein said wire has sixlongitudinally extending lobes defining a like number of longitudinallyextending grooves.
 10. A welding electrode comprised of: a steel wirehaving a plurality of longitudinally extending lobes defining aplurality of longitudinally extending grooves in the surface of saidwire; said grooves containing a plurality of shielding metals, one ofwhich is lithium, plus one or more shielding metals selected from theclass consisting of barium, cadmium, zinc, magnesium, strontium, sodium,potassium, calcium and bismuth, said lithium comprising 10-25 percent ofsaid shielding metals.
 11. The electrode of claim 10 wherein said metalsare comprised of lithium and aluminum in approximate ratios of 10-25percent lithium and the balance comprising aluminum.
 12. The electrodeof claim 10 wherein said metals are comprised of at least 10-25 percentlithium and the balance is comprised of one or more metals selected fromthe class consisting of aluminum, manganese, lead, magnesium, copper,silver, tin, nickel, cadmium and zinc, sodium, potassium and calcium.